Bulletin of the American Physical Society
2019 Fall Meeting of the APS Division of Nuclear Physics
Volume 64, Number 12
Monday–Thursday, October 14–17, 2019; Crystal City, Virginia
Session RF: Muon-Proton Scattering |
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Chair: Evie Downie, George Washington University Room: Salon 6 |
Thursday, October 17, 2019 8:30AM - 8:42AM |
RF.00001: The Role of Lepton Mass in QED Corrections for Muon Scattering on a Nucleon. Andrei Afanasev In order to address the proton radius puzzle through measuring the muon-proton and electron-proton elastic cross sections in the same experiment (MUSE), QED corrections have to be taken into account. In this talk, we will report both kinematic and dynamical sources of the differences between muon-nucleon and electron-nucleon elastic scattering. In addition, single-spin asymmetries caused by muon beam polarization will be shown to affect the scattering cross section at 0.1 per cent level. Novel effects due to the lepton mass are incorporated into a Monte-Carlo code ELRADGEN. [Preview Abstract] |
Thursday, October 17, 2019 8:42AM - 8:54AM |
RF.00002: Hyperfine splitting in muonic hydrogen and two-photon exchange on nucleons Oleksandr Tomalak Future precise measurements of the ground state hyperfine splitting (HFS) in muonic hydrogen by CREMA and FAMU collaborations as well as at J-PARC will provide strict constraints on the low-energy proton structure. Two-photon exchange (TPE) enters as a leading proton structure correction to HFS. Exploiting the precise 1S HFS measurements in electronic hydrogen, I will extract the TPE correction and make an accurate prediction for the HFS in muonic hydrogen. Moreover, I will present TPE correction to the Lamb shift and HFS on the neutron inside a nucleus and contrast it with the correction on the proton. [Preview Abstract] |
Thursday, October 17, 2019 8:54AM - 9:06AM |
RF.00003: The Muon Proton Scattering Ex[eriment (MUSE) Evangeline Downie The proton radius puzzle began in 2010 when the CREMA Collaboration released their measurement of the proton radius (Pohl et. al (2010)) from muonic hydrogen spectroscopy: rp=0.84184(67) fm, This was five standard deviations smaller that the accepted CODATA value at that time (0.8768(69) fm), and sparked an enduring and intriguing puzzle MUSE, the {MUon proton Scattering Experiment}, was first proposed in 2012 to be the first muon proton elastic scattering experiment with sufficient precision to address the proton radius puzzle. MUSE has the capacity to simultaneously measure elastic muon-proton, and electron-proton scattering, and switch polarities to measure with opposite charge states. As such, MUSE can directly measure the two-photon effect by comparing charge-states, and compare muon and electron scattering with minimal systematic error. We will review the motivation for and status of MUSE, which is due to begin production running in 2019. [Preview Abstract] |
Thursday, October 17, 2019 9:06AM - 9:18AM |
RF.00004: MUSE experiment status - Recent test program Shraddha Dogra The Muon proton Scattering Experiment (MUSE) uses the PiM1 beam line of the Paul Scherrer Institute is aiming to simultaneously measure elastic scattering of electrons and muons from a liquid hydrogen target to extract the charge radius of the proton. By comparing the two measured scattering cross sections, the experiment will provide more data for the proton radius puzzle and determine if the radius is the same when using different particle types in obtaining the proton radius. This presentation will show test run results from the summer 2019 beam time, which is measuring detector performance and beam properties, and performing initial cross section tests [Preview Abstract] |
Thursday, October 17, 2019 9:18AM - 9:30AM |
RF.00005: Recent Test Results and Experiment Status at MUSE Wan Lin The Muon proton Scattering Experiment (MUSE) at the PiM1 beam line of the Paul Scherrer Institute is aiming to simultaneously measure elastic scattering of electrons and muons from a liquid hydrogen target to extract the charge radius of the proton. By comparing the two scattering cross sections, the experiment will provide more data for the proton radius puzzle and determine if the radius is the same when using different particle types in obtaining the proton radius. This presentation will show test run results from the summer 2019 beam time, which is measuring detector performance and beam properties, and performing initial cross section tests. [Preview Abstract] |
Thursday, October 17, 2019 9:30AM - 9:42AM |
RF.00006: The Liquid Hydrogen Target for MUSE Haley Reid The MUon Scattering Experiment (MUSE) at the Paul Scherrer Institute (PSI) in Switzerland aims to resolve the proton radius puzzle by simultaneous high precision measurements of elastic scattering of muons and electrons from a liquid hydrogen target. MUSE requires a target system with a vertically movable assembly that can accommodate five target positions. The main target is a cylindrical Kapton-wall cell with copper end caps containing 280 mL of LH2. Other target positions are for a dummy cell, two solid targets for vertex reconstruction and detector alignment, and an empty position. In this presentation we report on the technical design and implementation of the target system and present data demonstrating the successful operation of the LH2 target. [Preview Abstract] |
Thursday, October 17, 2019 9:42AM - 9:54AM |
RF.00007: Understanding the Paul Scherrer Institute's PiM1 Beamline for MUSE Ethan Cline The MUon proton Scattering Experiment (MUSE) at the PiM1 secondary beam line of the Paul Scherrer Institute will simultaneously measure elastic scattering of electrons and muons from a liquid hydrogen target to extract the charge radius of the proton. By comparing the two scattering cross sections, the experiment will shed light on the proton radius puzzle and test lepton universality and the two-photon exchange. This talk will present results from the summer 2019 beam studies. It will be shown how the beam line can be used as a relative momentum spectrometer to extract the momentum of each particle species in the beam. The understanding of the production source distributions will also be presented. [Preview Abstract] |
Thursday, October 17, 2019 9:54AM - 10:06AM |
RF.00008: Nuclear polarization and the Lamb shift in muonic deuterium Samuel Emmons, Chen Ji, Lucas Platter For atoms such as electronic or muonic hydrogen or deuterium, the spectroscopic measurement of the 2S-2P Lamb shift is a good path to arrive at an estimate of a finite nuclear size. However, in such a measurement, three different quantities make contributions, and experiments cannot untangle them from each other. The three contributions to the Lamb shift come from the effects of QED, the finite size of the nucleus, and two-photon-exchange (TPE) between the orbiting lepton and the nucleus. If one desires to know the finite mean-square charge radius, theoretical calculations of the QED and TPE contributions must be made, and the precision with which one knows the radius from the Lamb shift calculation will be limited by uncertainties in these other calculations. The QED contributions to the Lamb shift are known very precisely. Calculations of the TPE part of the Lamb shift have been made for several light nuclei, including muonic deuterium. We present the preliminary results of a new calculation of the portion of the TPE correction coming from the polarization of the nucleus in muonic deuterium. We utilize pionless effective field theory (EFT) in this effort, which has the promise of providing a systematic way of reducing error in the TPE shift estimate. [Preview Abstract] |
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